When data is encoded to have redundancy, an error correcting code enables the correction of errors having occurred in the data. As such an error correcting code, an iterated code exists. In these years, a graph code that is a code system higher in correcting capability is also proposed.
The graph code is a code whose component codes are formed of combinations based on a graph theory. When information words are encoded using a generator matrix as the encoding method of the graph code, the size of the generator matrix is large. Thus, the scale of a data-saving circuit to store data necessary for encoding and the size of memory for encoding may be large.